I am badly wanting a sorority (not to breed, just because I think they're beautiful). I currently have my lone male, Sam, in a 12g Fluval Edge, but I have bought a Fluval Chi to place on my desk and would like having his company there instead (though he may not be crazy about the downgrade, as he is really rocking that Edge with bubble nests).

Sam goes *all over* the Edge, top to bottom, and enjoys every square inch of it. I wanted to ask how many betta females I could have in it if I put him in the Chi, or if it's even suitable. Opinions?

This tank is the more square shaped one with less surface area, correct?

The only concern I have with the tank itself is the smaller surface area, but that by no means makes it impossible to have a sorority in. Volume wise, its bigger than my ten gallon. I have 6 girls and I personally wouldn't go lower than that.

I planned my tank for 3 and a half months, though. Its really important that you do it the right way and there are lots of things to consider.
-where you get your girls (young girls or siblings from breeders is really the best choice)
-filtration. You need to do a fishless cycle or NPT
-live plants (good even with a cycled filter)
-decor. Cover the tank top to bottom
-QT, at least 2 weeks
-QT set up and a plan to cup all the girls before releasing
-caves. Just don't get any with few holes as they can be traps for girls being chased
-meds. I recommend Kanaplex because dropsy symptoms and columnaris seem to be common in sororities. I also recommend VitaChem and stress coat to help with fins because you will see fin nips and tears.

Oh, boy. Am I missing anything?

Good preparation is going to make the difference between a successful sorority and a complete failed sorority.

Ayala, thank you. I have a ton of aquarium plants (java fern, banana plants, dwarf tears, etc.) arriving tomorrow, and I really am interested in doing an NPT. I could transfer Sam to the Chi, set it up with part of the substrate and rocks from the Edge, and leave part of the Edge rocks there to help with the cycle (once it finishes cycling--I think I am a few days away still but am in no rush for the sorority). Of course, it doesn't even seem that cycling matters with an NPT, and I truly am interested in doing one.

If I did a sorority, I'd like to invest in getting a variety of colors of girls from one Thai breeder. The import bettas are so beautiful, and I think it would be better to handle it that way. Do you think I could have seven in the 12g Edge, perhaps?

It is possible. If the breeder keeps all their females in a big sorority they will probably be more socialized.

I would just make sure how many you can ship in one order. I know many breeders can ship a maximum of 6 bettas in one box, and shipping from Thailand is already going to cost a bit more than getting the girls in the US. I've personally found that US breeders have better deals on multiple fish orders.

I guess the primary thing I worry about is that the Edge has only a small area to which fish can come to the surface. I do wonder if the girls might fight if many of them want to be in that same place at once.

It's possible. You need tall plants that reach the surface or go past it. I have silk plants right now to fill in until the live ones grow.

In the beginning, I had one girl who liked to patrol the middle of the tank and she chased off any girl who came up to the middle for air. As soon as the girl being chased turns a corner around a plant and the aggressor can't see her, the chasing stops. My other girls found places in the tank to get air where Stella couldn't see them.

But TBH, I haven't had a lot of fighting, and they don't really chase anymore. My two EE girls have had the most fin damage - mostly straight tears (these heal in 24 hours) and one is missing a small chunk in her pectoral fin. My purple female also is missing a piece out of her tail fin and had some straight tears.

They will actually stay pretty close to each other, especially when you approach the tank. Given about two weeks all the fighting will likely sort itself out. You may be alarmed by it but its usually best to leave them and let the girls figure it out on their own. Only time to intervene is if two girls go at each other and neither backs down.

Also, they say you need surface area and, yeah, this is important obviously and a good idea if you've got a girl chasing all the others away from the surface, but when I'm looking away my girls really explore the entire tank, not just the top. I have even seen my girls sleep on the gravel or low in plants.

I guess the primary thing I worry about is that the Edge has only a small area to which fish can come to the surface. I do wonder if the girls might fight if many of them want to be in that same place at once.

You can lower the water level to just a fraction of an inch below the top glass... that's what I do any way and it works great. And FWIW, a lot of people with this tank don't seem to have problems with their betta's when the tank is filled up all the way. (although I haven't tried it)

I have mine filled all the way up now, and my boy betta doesn't have an issue with it at all. He's incredibly happy with it. It took him maybe half an hour to get the hang of where the hole was, but then he was fine.

I am badly wanting a sorority (not to breed, just because I think they're beautiful). I currently have my lone male, Sam, ...
Sam goes *all over* the Edge, top to bottom, and enjoys every square inch of it. I wanted to ask how many betta females I could have in it if I put him in the Chi, or if it's even suitable. Opinions?

zero since you will not be breeding, the male will attack the female if it is not mating time.

If only 100% sorority in the 12g Edge, 7 would be max with no other livestock IMO.